Coriolis effect

the apparent deflection (Coriolis acceleration) of a body in motion with respect to the earth, as seen by an observer on the earth, attributed to a fictitious force (Coriolis force) but actually caused by the rotation of the earth and appearing as a deflection to the right in the Northern Hemisphere and a deflection to the left in the Southern Hemisphere.

The observed effect of the Coriolis force, especially the deflection of objects or substances (such as air) moving along the surface of the Earth, rightward in the Northern Hemisphere and leftward in the Southern Hemisphere. The Coriolis effect is named after the French engineer Gustave Gaspard Coriolis (1792-1843).

An apparent force ultimately due to the rotation of the Earth. It is the Coriolis effect that makes the air in storms rotate counterclockwise in the northern hemisphere and clockwise in the southern hemisphere.